We need to understand the mechanisms of drug resistance in order to prevent it, in addition to informing subsequent treatment decisions. In this interview, Constantine Tam, MD, FRACP, FRCPA, of Peter MacCallum Cancer Centre, Melbourne, Australia, discusses our current knowledge of the mechanisms of resistance to venetoclax and ibrutinib. He highlights how, interestingly, the usual mutation of the primary therapeutic target has not been found in venetoclax resistant patients thus far. This video was recorded at the American Society of Hematology (ASH) 2017 Annual Meeting and Exposition in Atlanta, GA.